1. Field
The present disclosure generally relates to integrated circuit (IC) packages and, more particularly, to leadframes and method of manufacturing leadframes for use in IC packages.
2. Description of the Related Art
The silicon chips on which integrated circuits are formed are so small that they are sensitive to damage and hard to handle, and many IC chips are packaged in enclosures that protect the chips and provide larger contact leads that can be attached to circuitry on substrates such as printed circuit boards. One common method of assembling an IC package of this type is to attach a “leadframe”, or “lead frame”, as a mechanical support to the die during its assembly. A portion of the leadframe is trimmed off, leaving only the leads that provide the external connections for the finished product. A leadframe comprises a “die paddle”, to which the die is attached, and “leads”, which provide external electrical connections. One method of connecting the die to the leads is by wirebonding small jumper wires from the die contacts to various leads. In other cases, a finger of the leadframe may overlay the die directly and be soldered directly to the die contact. Lead frames are constructed from flat sheet metal either by stamping or etching. “Downsetting” consists of pushing the die paddle down relative to the bonding fingers in compliance with standard industry requirements. FIG. 1 illustrates an example of a leadframe with a die paddle that has been downset. FIG. 2 illustrates an IC package that has been cut away to show the IC die and the leads that remain after the leadframe is trimmed and formed.
It is also possible to assemble a number of IC chips onto a small substrate and package this assembly to form an IC device. As the number of IC chips and single devices being integrated into a single device increase, the package size grows and the amount of heat being generated by the IC devices increases. One approach to keeping the size of the integrated package down has been to stack IC chips, which presents challenges in providing interconnects and heat dissipation.